1. Technical Field
The present invention relates in general to an improved hard disk drive design and, in particular, to an improved design for a hard disk drive having a balance clip holder feature on the spindle motor with a stainless steel motor hub and a nickel-filled Teflon coating on the balance clips for reducing friction during clip adjustment in the disk pack balance process.
2. Description of the Related Art
Generally, a data access and storage system consists of one or more storage devices that store data on magnetic or optical storage media. For example, a magnetic storage device is known as a direct access storage device (DASD) or a hard disk drive (HDD) and includes one or more disks and a disk controller to manage local operations concerning the disks. The hard disks themselves are usually made of aluminum alloy or a mixture of glass and ceramic, and are covered with a magnetic coating. Typically, one to six disks are stacked vertically on a common spindle that is turned by a disk drive motor at several thousand revolutions per minute (rpm).
A typical HDD also utilizes an actuator assembly. The actuator moves magnetic read/write heads to the desired location on the rotating disk so as to write information to or read data from that location. Within most HDDs, the magnetic read/write head is mounted on a slider. A slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirably contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions on its air bearing surface (ABS) that enables the slider to fly at a constant height close to the disk during operation of the disk drive. A slider is associated with each side of each platter and flies just over the platter's surface. Each slider is mounted on a suspension to form a head gimbal assembly (HGA). The HGA is then attached to a semi-rigid actuator arm that supports the entire head flying unit. Several semi-rigid arms may be combined to form a single movable unit having either a linear bearing or a rotary pivotal bearing system.
The head and arm assembly is linearly or pivotally moved utilizing a magnet/coil structure that is often called a voice coil motor (VCM). The stator of a VCM is mounted to a base plate or casting on which the spindle is also mounted. The base casting with its spindle, actuator VCM, and internal filtration system is then enclosed with a cover and seal assembly to ensure that no contaminants can enter and adversely affect the reliability of the slider flying over the disk. When current is fed to the motor, the VCM develops force or torque that is substantially proportional to the applied current. The arm acceleration is therefore substantially proportional to the magnitude of the current. As the read/write head approaches a desired track, a reverse polarity signal is applied to the actuator, causing the signal to act as a brake, and ideally causing the read/write head to stop and settle directly over the desired track.
During manufacturing of the hard disk drive, the sub-assembly of the spindle motor is fabricated and the disks are attached to a hub 11 (FIG. 8) of the spindle motor. In the prior art, the hubs 11 are formed from aluminum, and balance clips 13 are used in the hubs to fine-tune the balance of the hubs 11. As shown in FIG. 8, the balance clips 13 are retained on the hub 11 in balance clip holder features 15, which are typically integrally formed as part of the motor hub 11. The holder features 15 and, thus, balance clips 13 and radially spaced apart from each other which requires more radial space and a motor bracket with a large diameter. As a result, the area use efficiency of the printed circuit board is reduced. Although this design is workable, an improved design would be desirable.